WO2009000250A2

WO2009000250A2 - Linear bearing with rotating rolling bodies and diverter for said type of linear bearing

Info

Publication number: WO2009000250A2
Application number: PCT/DE2008/001036
Authority: WO
Inventors: Stefan GLÜCK
Original assignee: Schaeffler Kg
Priority date: 2007-06-28
Filing date: 2008-06-21
Publication date: 2008-12-31
Also published as: WO2009000250A3; DE102007030004A1

Abstract

The invention relates to a linear bearing with rotating rolling bodies (04) provided with a straight, load-bearing rolling section (07), a straight, load-free return section (11) that is arranged parallel with respect to the rolling section (11) and two diverters (12) which are arranged between the rolling section and the return section and guides the movement of the rolling bodies (04) between the running section (07, 11) in a diverter channel (14) such that a continuous revolution of the rolling body (04) is possible. According to the invention, at least one of the two diverters (12) comprises a section that can be actively deformed by an actuator (17), thus actively influencing the movement of the rolling bodies (04) on the intersection between the diverter (12) and the load-bearing running section. As a result, this increases the service life and minimises the noise of said bearings.

Description

Linear bearing with rotating rolling elements and deflector for such a linear bearing

description

Field of the invention

The invention relates to a linear bearing with rotating rolling elements. Such linear bearings have a straight load-bearing running section and a load-free return section arranged parallel thereto for the rolling elements. Running section and return section are connected by deflectors. In particular, the invention relates to linear bearings (also called circulation body) or circulating units for linear guides with unlimited stroke or travel, as found, for example, in the frequently used profiled rail rolling guide with a carriage application. The invention further relates to a deflector for such linear bearings.

Linear bearings with rotating rolling elements are used in a wide variety of linear guide units for the realization of large travel distances. Since the rolling elements run here in an endless loop, the travel is limited only by the length of the rail. Depending on the embodiment, balls or rollers are used as rolling elements. The load-bearing parts of such linear bearings are usually made of a rolling steel, the deflector and the return section depending on the load and type often made of plastic or aluminum. The rolling elements, the deflector and the running and return track experienced at the inlet of the rolling elements in the deflector each large loads, which are reflected in the life, bearing capacity and noise of the linear bearing. In conventional full-spherical linear bearings on the one hand, the rolling elements are pulled down under full load from the running section in the deflector, on the other hand thrown from the deflector in the return section. The deflector deforms under the force applied by the rolling elements. Due to the passive deformation, the deflector swings dynamically around its initial position after deformation. When entering the next rolling element can thus lead to unfavorable situations in which the rolling elements are not ideally braked or accelerated. This increases in particular the wear of the deflector.

From the prior art, many efforts are known to improve the running properties of the rolling elements of such linear bearings and to increase the service life. This also includes many attempts, in particular to optimize the inlet geometry of the deflecting body.

DE 30 23 978 C2 describes a linear bearing with bars in the load-bearing section, in which a simple and smooth rolling element circulation is achieved with a simple production. The entire return channel is composed of two form-fitting assembled return shells. As a result, only a two-time interruption of the circulation channel takes place at the ends of the supporting raceway section. The return channel itself runs bumpless.

For example, from EP 0 846 880 B1 it is known to use rolling element chains in linear bearings. Around the critical area of the deflection of the rolling elements and in this the collision of the balls as well as ex- To prevent treme load changes, the rolling elements are connected by a chain and thereby controlled and separated from each other by the circulation. As a result, in particular the noise level is lowered and a higher possible running speed in the guide is achieved.

Closed Wälzkörperketten are better suited to compensate for the extreme load changes at least somewhat. The problem is still the extreme load changes on the rolling elements at the transition from the running section in the return channel and vice versa, since the rolling elements run normalalkraftfrei in the return channel. When running into the running section thus suddenly resulting from the guide load Wälzkörpernormormalkraft is effective while abruptly eliminated when entering the deflector.

The invention is therefore based on the object to reduce the extreme load changes in the transition of the rolling elements of the running section in the return channel and when re-steering in the running section and thereby reduce in particular the wear and the noise level in linear bearings.

The object is achieved by a linear bearing with the features of claim 1. According to the invention, a deflector is proposed in a generic linear bearing, which is provided with an actively deformable portion, wherein an actuator is provided for deformation.

The advantages of the invention are to be seen in particular in that there is an active support of the acceleration and braking processes in the linear bearing by the deflector.

Preferably, an actuator is provided on the deflector, which has a flexible tongue as a deformable portion. When lifting the rolling element of the career of the actuator catches this softening of the tongue from softer. It is also possible to actively raise the rolling element under the action of the actuator on the track, ie to act on the rolling elements with a pulse of the flexible tongue to make the transition to the load zone softer and thus gentler material. Constructively two separate actuators can be used at the deflector, one of which is effective at the inlet and one at the outlet of the deflector.

The actuator is in a preferred embodiment, a piezoelectric actuator element. For this purpose, in particular a bimorph actuator (bending element) is considered. A bimorph is composed of two thin plates of a piezoelectric material (transverse stretching elements), between which a metal layer is arranged as a central electrode. If a voltage is applied between the central electrode and the outer electrode, one plate becomes longer due to the reverse polarization, while the other one is shortened. This causes a bending deflection.

Bending transducers are available in different versions (also monomorphic and multimorphic) and can be dimensioned and selected by the specialist depending on the application. The actuator may also be formed by an electroactive polymer.

In order to determine the right time for the required deformation, the linear bearing preferably further comprises at least one sensor, which is arranged, for example, in the return section and / or in the running section shortly before the inlet of the rolling element in the deflector and provides a signal for deformation of the actuator.

The correct point in time for activation of the actuator, however, can also be determined, for example, from the determination of the running speed of the rolling elements, taking into account the parameters of the linear bearing. Alternatively, the actuator itself can be used as a sensor by detecting an incipient deformation caused by the rolling-element inlet and thus the actuator can be actuated in the correct time.

The actuation of the actuator is designed in a further preferred embodiment so that the tongue of the deflector is calmed down again so quickly that the occurring and normally longer-lasting oscillation is already subsided until contact with the next rolling element. For this purpose, the actuator after the rolling element contact stiffen the tongue or actively create a counter-vibration for reassurance. For this purpose, a suitable drive circuit is provided.

A further modified embodiment of the invention proposes a self-sufficient solution in which the energy delivered by the rolling element to the deflector is used to activate the deflector at the other end of the running section, without an external power supply being necessary. Here, a generator element is arranged at the inlet of the rolling elements in the first deflector, which generates energy by deformation, which is used for in-phase control of the actuator on the opposite Umlenker when lifting the rolling elements of the barrel section.

To ensure this function for both directions of movement of the linear bearing, a generator element and an actuator must be provided on each side or on each deflector. Alternatively, piezoelectric ceramic components or electroactive polymers can be used here, which can act as generator and actuator. Piezoelectric ceramic devices are electromechanical transducer components. These are able to convert mechanical forces such as pressure, strain or acceleration into an electrical voltage or charges and to convert an electrical voltage into mechanical motion or vibrations. A preferred embodiment of the invention is illustrated in the figures and will be explained in more detail below. Show it:

1 shows a profiled rail Wälzführung with rotating rolling elements according to the prior art.

2 shows three views of a deflector according to the invention in a schematic representation;

3 shows a detail of a linear bearing in a schematic sectional illustration on a first deflector;

Fig. 4: a second deflector on the linear bearing according to FIG. 3 in a schematic sectional view.

Fig. 1 shows a known from the prior art profiled rail Wälzführung in a partially sectioned view. A carriage 01 is guided on a straight extending rail 02. In the carriage 01 four linear bearings 03 are arranged with rotating rolling elements 04 such that upon a movement of the carriage 01, the rolling elements 04 along tracks 06, which are incorporated in the rail 01, roll.

The linear bearing 03 comprises a load-bearing running section 07 and a roller circulation channel, which is composed of a first deflector 08, a second deflector 09 (in the uncut area of the illustration) and a load-free return section 11.

The life cycle of a linear bearing and the noise particularly influencing already described load changes occur at the transition of the rolling elements 04 from the barrel section 07 in the first deflector 08 and the transition from the second deflector 09 in the barrel section 07. In Fig. 2, a deflector 12 of a linear bearing according to the invention is shown, which according to the invention replaces the first and second deflectors in the linear bearing 03. In this case, Fig. A) shows a schematic side view and Fig b) and c) is a sectional view of the deflector 12 according to the invention.

The deflector 12 according to the invention shown in Fig. A) of FIG. 2 comprises a tongue 13 and a deflection channel 14 through which the rolling elements 04 are supplied to the return section 11 and the running section 07, respectively. Preferably, the deflector 12 has a lubricating opening 16, through which a lubricant can be supplied to the linear bearing. For lubricant-free bearings this opening can of course be omitted.

In Fig. B), an actuator 17 is shown in the sectional view, which is integrated in the tongue 13 and is mounted outside of the deflection channel 14 at this. The actuator 17 is preferably a piezoelectric actuator (Bimorph). However, it is also within the scope of the invention to produce the tongue 13 at least in sections from an electroactive polymer. The actuator 17 is able to cause a corresponding movement of a movement 18 of the tongue 13, as indicated by the movement arrow 18 and the dashed lines. The movement of the tongue 13 takes place substantially in the direction of the adjacent running section 07, so that the tongue 13 can escape a rolling body entering the deflector by a predetermined amount or can follow a rolling body running out of the deflector.

Fig. 3 shows a detail of a linear bearing according to the invention at the outlet of the rolling elements from the running section in the deflector. The linear bearing is attached to a carriage, not shown, which is moved in the direction of the movement arrow 19 along the rail 02. The rolling elements 04 roll between the running section 07 of the linear bearing and the track 06 of the rail 02 to the deflector 12 and are lifted from the tongue 07 of the track 07. At this moment, the actuator 17 actively brings about a deformation 21 in order to intercept the rolling element 04 more efficiently, ie to give way to its movement by a predetermined amount. Subsequently, the rolling elements is deflected by the deflection channel 14 in the return section 11.

FIG. 4 shows, in a schematic sectional illustration, the inlet of the rolling elements 04 from the return section 11 into the running section 07. The carriage also moves in the direction of the movement arrow 19. In this figure, it is shown how the inlet of the rolling elements 04 can be optimized with a linear bearing according to the invention.

The rolling element 04 is deflected from the return section 11 through the deflection channel 14 between the running section 07 of the linear bearing and the track 06 of the rail 02 and thereby supported by a deformation 22 of the tongue 13 in the direction of the running section 07 by the actuator 14 at the required acceleration.

LIST OF REFERENCE NUMBERS

01 - carriage

02- profile rail

03- linear bearings

04 rolling elements

05-

06- career

07- running section

08- deflector, first

09- deflector, second

10- -

11 - return section

12- deflector

13- tongue

14- deflection channel

15-

16- lubrication opening

17- actor

18- motion arrow

19- movement pfei)

20-

21 - Deformation

Claims

claims

1. Linear bearing with rotating rolling elements (04) with

a straight, load-bearing running section (07),

a straight, load-free return section (11) arranged parallel thereto, and two deflectors (12) which are arranged between the running section (07) and the return section (11) and the movement of the rolling bodies (04) between the running sections (07, 11) in a deflection channel (14), so that a continuous circulation of the rolling bodies (04) is possible, characterized in that at least one of the deflectors (12) by an actuator (17) actively deformable portion (13).

2. Linear bearing according to claim 1, characterized in that the two deflectors (12) by an actuator (17) actively deformable portion (13).

3. Linear bearing according to claim 1 or 2, characterized in that the actuator (17) is an electroactive polymer or a piezoelectric actuator element.

4. Linear bearing according to one of claims 1 to 3, characterized in that it further comprises at least one sensor which detects the inlet of the rolling elements (04) in the equipped with the actuator (17) deflector (12), wherein the sensor signal for controlling the actuator (17) is used.

5. Linear bearing according to claim 4, characterized in that the sensor is a pressure sensor or a position sensor.

6. Linear bearing according to claim 4 or 5, characterized in that sensor and actuator (17) are realized in a single piezoceramic element o- in a single electroactive polymer.

7. Linear bearing according to one of claims 1 to 6, characterized in that the deformable portion of the deflector (12) is designed as a tongue (13) to which the actuator (17) is attached.

8. Linear bearing according to claim 7, characterized in that the tongue (13) by actuation of the attached actuator (17) by a predetermined path in the direction of the adjacent load-bearing running portion (07) is deflectable.

9. linear bearing according to claim 7 or 8, characterized in that the actuator (17) and the tongue (13) are integrally formed.

10. deflector (12) for a linear bearing with a deflection channel (14) for guiding rolling elements (04) between a running section (07) and a return section (11) of the linear bearing, characterized in that it is activated by an actuator (17) includes deformable portion (13).